What is a corrosion inhibiting admixture?
Corrosion inhibiting admixtures are concrete additives that extend the life of the structure without corrosion (extends the time to corrosion initiation) or significantly reduces the corrosion rate of embedded metal. Certain admixtures can be a mixture of the two, providing double benefits to your structure.
There are four main types of corrosion inhibiting admixtures. Their dosage is dependent upon many factors including cement types, temperatures, environment, etc.
How are corrosion inhibiting admixtures classified?
There are three main elements that help classify the type of admixture that a product belongs to. First is the electrochemical mechanism of action, including anodic, cathodic, or a combination. Second is the type of chemical used, whether it is organic or inorganic. Lastly, you can use the kind of substance it comes in (liquid, powder, etc.) as a classification method.
What are the types of corrosion inhibiting admixtures?
Amine Carboxylate is available in both a concentrated liquid and a powder form. This specific corrosion inhibiting admixture is absorbed onto the reinforcing steel bar’s surfaces and creates a protective molecular layer. This protective amine carboxylate layer prevents any further corrosion and reactions between the corroding compounds and the embedded reinforcements. Especially effective in seawater environments, protecting concrete from salt exposures.
Calcium Nitrate is another corrosion inhibiting admixture. It is available in percentage solutions which can be adjusted per the desired effect and specifics of a project. Calcium nitrate is categorized as an anodic inhibitor which means it interferes with chloride complexing processes by oxidizing the more easily attacked form of iron to the more stable form. Calcium nitrate is not applicable for poor quality concrete. Calcium nitrate also is an accelerator of both set and strength development of concrete, which should be adjusted if used in poured concrete.
Organic alkenyl dicarboxylic acid salt is a water-based solution that is also used as a corrosion inhibiting admixture. It is also known as DSS. It is a dual action corrosion inhibiting admixture as it affects the anodic reaction of the steel as well as restricts moisture used in the cathodic reaction. It is also proper for use in reducing chloride induced corrosion of properly proportioned concrete from seawater, salt-laden air, and deicing exposure.